Atomic layer deposition with point of use generated reactive gas species

ABSTRACT

An apparatus for atomic layer deposition preventing mixing of a precursor gas and an input gas. From the apparatus a flow of the input gas is provided over a surface of the workpiece wherein a beam of the electromagnetic radiation is directed into the input gas in close proximity to the surface of the workpiece, but spaced a finite distance therefrom. The input gas is dissociated by the beam producing a high flux point of use generated reactive gas species that reacts with a surface reactant formed on the surface of the workpiece by a direct flow of the precursor gas flown from the dispensing unit. The surface reactant and reactive gas species react to form a desired monolayer of a material on the surface of the workpiece.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of application Ser. No. 10/091,938,filed Mar. 5, 2002, now U.S. Pat. No. 6,730,367, which related to patentapplication Ser. No. 09/998073 for Q‘A Method to Provide High Flux ofPoint of Use Activated Reactive Species for Semiconductor Processing,”filed on Nov. 30, 2001, now U.S. Pat. No. 7,001,481.

BACKGROUND OF THE INVENTION

The invention pertains to semiconductor processing and in particular, toan improved atomic layer deposition apparatus using a point of usegenerated reactive gas species for semiconductor processing.

Atomic layer deposition (ALD), also known as atomic layer epitaxy (ALE)and atomic layer chemical vapor deposition (ALCVD), offers manyadvantages over the traditional deposition methods. ALD relies onself-limiting surface reactions in order to provide accurate thicknesscontrol, excellent conformality, and uniformity over large areas. As themicroscopic features on a chip grow increasingly narrow and deep, theseunique features make ALD one of the most promising deposition methods inthe manufacturing of the future circuits.

The feature that makes ALD a unique deposition method compared tochemical vapor deposition (CVD) is that it deposits atoms or moleculeson a wafer a single layer at a time. Additionally, ALD films aredeposited at temperatures significantly lower than comparable CVDprocesses, thereby contributing to lower thermal exposure of the waferduring processing. Furthermore, as another distinction from CVD methods,no strict precursor flux homogeneity is required in ALD because of theself-limiting growth mechanism. The flux has only to be large enough tofully saturate the surface with the given reactant. This enables, forexample, the utilization of low vapor pressure solids, which aredifficult to be delivered at constant rates.

ALD accomplishes deposition by introducing gaseous precursorsalternately onto a workpiece such as, for example, semiconductorsubstrate or wafer. Under properly adjusted processing conditions, i.e.,deposition temperature, reactant dose, length of precursor, and purgepulses, a chemisorbed monolayer of a first reactant is left on thesurface of the workpiece after a purge sequence. Typically, the purgesequence is completed by evacuating or purging the entire reactorchamber. Afterwards, the first reactant is reacted subsequently with asecond reactant pulse, such as a flux of a generated reactive gasspecies, to form a monolayer of a desired material along with anygaseous reaction byproducts, such as when compounds are used asprecursors. The surface reactions are self-controlled and produce nodetrimental gas phase reactions, thereby enabling accurate control offilm thickness by counting the number of deposition cycles.

In one particular ALD method, there is a high degree of interest inusing a point of use generated reactive gas species. However, for ALDprocesses, it is difficult to generate a high flux of short-livedreactive gas species on the surface of the wafers and cycle it through anumber of on/off states at a fast rate required for high throughput ALDprocesses.

SUMMARY OF THE INVENTION

The present invention solves the above-mentioned difficulties byproviding an improved atomic layer deposition method and system. Inparticular, a dispenser unit according to the present invention is usedwith a point of use generated reactive gas species for atomic layerdeposition, which permits the cycling of the system through a number ofon/off states at a fast rate for higher processing throughput.

In a reaction chamber containing a workpiece, a precursor gas is flowndirectly onto an exposed surface of the workpiece from the dispenserunit to form a surface reactant thereon. Additionally, an input gas isflown in through a side of the dispenser unit. The flows of precursorand input gases are separated by a pump/purge setup on the dispenserunit designed to prevent mixing. As the workpiece is scanned under thedispenser unit to form the surface reactant, the input gas is exposed toa focused beam of electromagnetic radiation. The electromagneticradiation dissociates a gaseous constituent of the input gas creatingthe high flux of point of use generated reactive gas species. Theincoming flux of the generated reactive gas species reacts with thesurface reactant in a complete and self-limiting reaction forming adesired monolayer of a material thereon. Multiple dispenser units can beused to increase the ALD process.

A system and apparatus for generating a high flux of short-livedactivated reactive gas species using transmission gas (es) is disclosedby commonly assigned patent application: Ser. No. 09/998,073 for “AMethod to Provide High Flux of Point of Use Activated Reactive Speciesfor Semiconductor Processing,” filed on Nov. 30, 2001, which is hereinincorporated fully by reference.

In one aspect, the present invention encompasses a method of chemicallytreating a surface of a workpiece. The method comprises exposing thesurface of the workpiece to a direct flow of a precursor gas to form asurface reactant thereon, and providing a flow of an input gas above thesurface of the workpiece. The method further comprises preventing themixture of the precursor gas and the input gas with a purge gas,directing a beam of electromagnetic radiation into the input gas toproduce a high flux of generated reactive gas species, and reacting thegenerated reactive gas species with the surface reactant.

In another aspect, the present invention encompasses a system forchemically treating a surface of a workpiece. The system comprises asupply of an input gas, a supply of a precursor gas, and a supply of apurge gas. A dispenser unit is adapted to expose the surface of theworkpiece to a direct flow of the precursor gas for a surface reactantformation, to provide a flow of the input over the workpiece, and toprovide the purge gas between the precursor gas and the input gas toprevent mixing of the precursor and input gases. The dispenser unitfurther includes a pair of evacuation ports for evacuating the purgegas. A source is adapted to converge a beam of electromagnetic radiationin the flow of the input gas in close proximity to the surface of theworkpiece, but spaced a finite distance therefrom, to dissociate theinput gas into a high flux of generated reactive gas species that reactswith the surface reactant to chemically treat the surface of theworkpiece.

In still another aspect, the present invention encompasses a dispenserunit adapted for use in a reaction chamber for atomic layer depositionof a material onto a surface of a workpiece. The dispenser unitcomprises a first gas port adapted to provide a flow on an input gasover the surface of the workpiece to be dissociated by a radiation beaminto a point of use generated reactive species. Further included is asecond gas port adapted to provide a direct flow of a precursor gas ontothe surface of the workpiece which by chemisorption forms a firstsurface reactant, and a third gas port adapted to flow a purge gas toprevent mixing of the input and precursor gases. Also provided is a pairof evacuation ports adapted to evacuation at least the purge gas.

These and other features and objects of the present invention will beapparent in light of the description of the invention embodied herein.

BRIEF DESCRIPTION OF THE DRAWINGS

The following detailed description of the embodiments of the presentinvention can be best understood when read in conjunction with thefollowing drawings, where like structure is indicated with likereference numerals and in which:

FIG. 1 is an enlarged cross sectional view of a workpiece during achemical treatment procedure according to the present invention;

FIG. 2 is a diagrammatic side view of a structure adapted to chemicallytreat a surface of a workpiece according to the present invention;

FIG. 3 is a diagrammatic top view of a structure adapted to chemicallytreat a surface of a workpiece according to the present invention; and

FIG. 4 is a process flow chart of a program which implements anembodiment of the atomic layer deposition method according to thepresent invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the following detailed description that follows, reference is made tovarious specific embodiments in which the invention may be practiced.These embodiments are described in sufficient detail to enable thoseskilled in the art to practice the invention, and it is to be understoodthat other embodiments may be utilized and that specific equipment,processing steps, energy sources, and other changes may be made withoutdeparting from the spirit and scope of the present invention.

The term “workpiece” as used herein includes semiconductor substrate,printed circuits, and other structures that may be chemically treated bythe method and system of the invention.

The terms “substrate” as used herein include any semiconductor-based orother structure having an exposed surface in which to form a structureusing the system or method of this invention. Substrate is to beunderstood as including silicon-on-insulator, doped and undopedsemiconductors, epitaxial layers of silicon supported by a basesemiconductor foundation, and other semiconductor structures.Furthermore, when reference is made to a substrate in the followingdescription, previous process steps may have been utilized to formactive devices, regions or junctions in the base semiconductor structureor foundation.

FIG. 1 discloses an improved atomic layer deposition method andapparatus according to the present invention providing a point of usegenerated/activated reactive gas species for processing a surface 2 of aworkpiece 4. A first precursor gas, indicated by 5, is flown directlyonto the surface 2 of the workpiece from a first gas port 6 a of adispenser unit 8. From a side of the dispenser unit 8, a flow of aninput gas 10 is provided from a second gas port 6 b in a direction awayfrom the flow of the precursor gas 5.

Between the first and second gas ports 6 a and 6 b, the dispenser unit 8further includes a pair of evacuation ports 12 a and 12 b, and a thirdgas port 6 c. As illustrated, juxtaposed to the first evacuation port 12a are the first and third gas ports, 6 a and 6 c, and juxtaposed to thesecond evacuation port 12 b are the second and third gas ports, 6 b and6 c. The third gas port 6 c is used to flow a purge gas, indicated by14, directly onto the surface 2 of the workpiece.

In a purge/pump sequence, as the precursor gas 5, input gas 10, andpurge gas 14 are flown from the dispenser unit 8, the pair of evacuationports 12 a and 12 b pump out any residuals/gases in their generalvicinity. By this arrangement, ports 6 c and 12 a–b on the dispenserunit 8 prevent the mixing of the precursor gas 5 and the input gas 10 bycreating a pump/purge barrier therebetween.

During processing, ALD pulse lengths are determined by the space betweenthe gas ports as well as a scan speed of workpiece. Accordingly, underproperly adjusted processing conditions (i.e., deposition temperature,reactant dose, and length of precursor and purge gases pulses), scanningthe workpiece 4 under the dispenser unit 8 in the direction indicated by“X”, leaves a chemisorbed monolayer of a surface reactant, illustratedby symbols “A”, on the surface 2 after the purge/pump sequence of thedispenser unit 8 with flows of the precursor gas 5 and purge gas 14.

While scanning the workpiece 4, a beam of electromagnetic radiation 16is directed into the input gas 10 producing at the point of use a highflux of short-lived generated reactive gas species, illustrated bysymbols “B”, by dissociating a gaseous constituent of the input gas 10.As the reactive gas species B reaches the surface 2 of the workpiece 4,reactants A and B react together in a complete and self-limitingreaction which forms a desired monolayer of a material, illustrated bysymbol S, on the surface 2 of the workpiece 4. Material monolayer S maybe an element or a compound. Therefore, the above-described multi-portdispenser unit 8 permits at the same time the formation of both surfacereactant A on a first portion of the surface 2 of the workpiece 4 andthe desired material monolayer S on a subsequent surface portion of theworkpiece.

The beam of electromagnetic radiation 16 may advantageously be providedas a converging laser beam. Additionally, to ensure that maximum energyis provided at the focal point of the laser beam, a transmission gas 18that is substantially nonattenuating to preselected wavelengths ofelectromagnetic radiation may be provided by a fourth gas port 6 d.Furthermore, the second gas port 6 b may be a nozzle providing a laminarflow of the input gas 10 over the surface 2 of the workpiece 4 such thatthe beam 16 converges in the flow in close proximity to the surface ofthe workpiece, but spaced a finite distance therefrom. This finitedistant is indicated by symbol “H.” It is to be appreciated that theinput gas is provided over the surface of the workpiece in a gas layerhaving a thickness that is at least large enough to accommodate thefinite distance H.

It is to be appreciated that a laminar flow prevents the input gas fromspiraling over the surface 2 of the workpiece 4, thereby minimizingnon-uniform distribution of the generated reactive gas species B.Baffles may be incorporated into the nozzle 6 b to break up the incominggas stream into the desired laminar flow. Furthermore, the width ofnozzle 6 b can be made adjustable to optimize the gas flow rate forparticular chemically treatments of the surface 2 of the workpiece 4.

With regard to distance H, the beam 16 is focused in proximity to thesurface 2 of the workpiece 4 such that maximum beam energy dissociatesat the point of use a gaseous constituent of the input gas 10 into thehigh flux of generated reactive gas species B. Preferably, distance H isless than a few mean-free-path lengths of the generated reactive gasspecies B, or from about 2 millimeters to about 4 millimeters above thesurface 2 of the workpiece 4. At a distance from about 2 millimeters toabout 4 millimeters, the generated flux of reactive gas species B iscloses enough in order to migrate to the surface 2, yet far enough thatthe focal point of the laser beam 16 does not inadvertently impact theworkpiece 4.

It is to be further appreciated that the laser beam 16 can dissociatemore than one generated reactive gas species B depending on thecomposition of the input gas 10, and also depending on the particularwavelength(s) of electromagnetic radiation present in the laser beam 16.Therefore, besides reducing energy losses of the laser at its focalpoint, the present invention also gives access to new, quicklydisappearing metastables that would otherwise disappear and never reachthe surface 2 of the workpiece if formed well above the wafer surface.In the next sections, the above-described methodology and apparatus isfurther disclosed by the exemplary embodiments of a processing system 20shown by FIGS. 2–4.

FIG. 2 is a diagrammatic sectional side view of the major componentparts of an exemplary embodiment of a processing system 20 having achamber 22 for containing the workpiece 4 to be processed. In a typicalexample, the workpiece 4 comprises a semiconductor wafer of 1 to 8inches in diameter and 0.127 to 0.89 mm thick, which is supported upon aconventional chuck 24.

The chamber 22 is sealable such that it may contain and hold asubambient pressure of from about 0.1 Torr to about 100 Torr of agaseous atmosphere, generally indicated by 26, which is supplied to thechamber from first and second gas sources 28 a and 28 b, respectively.As illustrated by FIG. 3, the first gas source 28 a is in gascommunication with the chamber 22, and provides the precursor and purgegases 5 and 14, and optionally, transmission gas 18. These gases eachmay be a single gas or a mixture of such gasses.

The second gas source 28 b is also in gas communication with the chamber22 and provides the input gas 10. Gases 5, 10, 14 and/or 18 areregulated in a conventional manner, such as for example, in-linepressure regulators 30 a and 30 b, values 32 a and 32 b, and mass flowmeters 34 a and 34 b. When introducing mixtures of gases in the chamber22, including other conditioning gas/gases to aid and/or inhibit suchchemical processes, conventional mixing chambers 36 a and 36 b may beused, if desired, to homogenize the gaseous mixture(s).

After completion of the ALD processes, the gaseous atmosphere 26 withinthe chamber 22 may be quickly evacuated by a first mechanical exhaustpump 38 a connected also in gas communication with the chamber via afirst exhaust valve 40 a. However, it is to be appreciated that unlikeprior art type chambers, the entire gaseous atmosphere 26 within thechamber 22 does not need to be purge or exhausted between pulse phasesof the ALD process due to the purge/pump set-up of the dispenser unit 8provided therein. As illustrated by FIG. 3, the pair of evacuation ports12 a and 12 b of the dispenser units are in gas communication with asecond mechanical exhaust pump 38 b and regulated by a second exhaustvalve 40 b for the above purpose.

The input gas 10 is a gas or mixture of gases that absorb predeterminedwavelengths of electromagnetic energy and dissociate to form the desiredgenerated reactive gas species B. Such gases that include: N₂0, NO₂,NH₃, H₂, H₂O, N₂, O₂, O₃, CCl₄, BCl₃, CDF₃, CF₄, SiH₄, CFCl₃, F₂CO,(FCO)₂, SF₅NF₂, N₂F₄, CF₃Br, CF₃NO, (CF₃)₂CO, CF₂HCl, CF₂HBr, CF₂Cl₂,CF₂Br₂, CF₂CFCl, CF₂CFH, CF₂CF₂CH₂, NH₃, CHF₃, fluorohalides,halocarbons, and combinations thereof. Such desired reactive gas speciesB include: NO, OH, NH, N, F, CF₃, CF₂, CF, NF₂, NF, Cl, O, BCl₂, BCl,FCO, and combinations thereof. It is to be appreciated that the choiceof input gas 10 employed in a photoreactive treatment procedure isguided by the type of chemically treatment process to be carried out.

The transmission gas 18, if used, is a gas or mixture of gases that isnon-attenuating to predetermined wavelengths of electromagneticradiation. Such transmission gasses, as well as the purge gas includeargon, nitrogen, helium, neon, and combinations thereof.

Depending on the particular parameters used in the chamber 22, otherconditioning gases may be used such as to absorb electromagneticradiation, to reduce the concentration of an reactive gas species, or asa catalyst for the reaction between the reactive gas species B and thereactant(s), such as surface reactant A. As such, a conditioning gas maybe employed for controlling the reaction rate between the reactive gasspecies B and reactant A, or for creating a minimum reaction energythreshold for limiting the production of undesirable reaction products(e.g., ozone and hazardous polymer-based reaction products).

Examples of conditioning gas molecules include nitrogen, helium andargon. Nitrogen acts mainly to impede the reaction between materialdeficient regions and reactant gases, while argon tends to impede thediffusion of the primary reactant gas molecules, rather than toparticipate in a reaction. Helium behaves in an intermediate mannerbetween nitrogen and argon.

The chamber 22 also contains a translation stage 42 to support theworkpiece 4 in the chuck 24 and to move it in and out of the chamber 22.The translation stage 42 is electrically driven, and moves the chuck 24and workpiece 4 held thereon back and forth within the chamber 22 at aconstant rate (e.g., about 6.5 mm/sec) specified by a controller 44. Asbest illustrated by FIG. 3, protruding banking pins 46 spaced by about120 degrees hold the workpiece 4 in place on the chuck 24.

In one embodiment, the translation stage 42 causes relative motionbetween the surface 2 of the workpiece 4, the dispenser unit 8, and thebeam 16 such that the precursor gas 5, purge gas 14, and beam 16 sweepsor scans over the surface 2 of the substrate 4 during processing. Inanother embodiment, the workpiece 4 may be held stationary duringprocessing, and the dispenser unit 8 and scanning optics 48 of a lasersystem 50 are moved to cause the desired relative motion between thesurface 2 of the workpiece 4, the dispenser unit 8, and the beam 16.

The laser beam 16 is shaped and delivered to the chamber 22 via theconventional laser system 50 that includes the scanning optics 48, alaser controller 52, and a laser source 54. In particular, the scanningoptics 48 typically comprises one or more mirrors 56 (only one of whichis shown) and focusing lenses 58. The mirrors 56 direct laser beam 16towards the focusing lens 58 which shapes the conventional rectangularcross-section beam 16 received from the laser source 54 into aconverging beam of electromagnetic energy proximate the surface 2 of theworkpiece 4.

In one embodiment, the focusing lens 58 forms part of a window 60 of thechamber 22, such as in the embodiment when relative motion is providedbetween the laser beam 16 and workpiece 4 by the translation stage 42.In other embodiments, the scanning optics 48 along with the focusinglens 58 move relative to the window 60 to provide the desired scanningof the surface 2 of the workpiece 4 with beam 16. The windows 60 may bequartz, sapphire, or zinc selenide. In still other embodiments, thefocusing lens 58 is a cylindrical refractive lens, and both the lens 58and window 60 are made from fused silica which allows visual inspectionof the chamber 22 during a photoreactive treatment procedure, which isuseful for monitoring the progress of a reaction as well as forend-point detection.

Additionally, although laser beam 16 is illustrated as a long narrowband 62 that extends across the major expanse of the surface 2 of theworkpiece 4 during processing, it is to be understood that laser beam 16can comprise other shapes. For example, the beam 16 may be provided as acircular beam which traverses across an entirety of the surface 2 of theworkpiece 4 along the shown X and Y axes. Alternatively, the beam 16 canbe configured to be wide enough to cover an entirety of the surface 2 ofthe workpiece 4 without being passed across such surface.

Laser source 54 may be an excimer laser (for example, a Cymer CX-2excimer laser available from Cymer Laser Technologies of San Diego,Calif., USA), which generates a pulsed beam 16 at wavelengths of 248 nmand 193 nm, and adapted to provide beam energy in the range of about 100to about 5000 mJ/cm². Other lasers could be used, e.g., a tunableAlexandrite solid state pulsed laser in combination with a frequencymultiplier. As shown in FIG. 2, the cross-sectional dimensions of thebeam 16 from the laser source 54 may be in the range of 3 mm×5 mm to 5mm×15 mm. The scanning optics 48 focuses beam 16 so that at distance Habove the surface 2 of the workpiece 4, the final beam gives theappearance of a knife-edge. In particular, the laser beam 16 canpredominantly comprise a single wavelength of ultraviolet light, andsuch wavelength can be chosen to interact with a specific constituent ofthe input gas 10.

A beam dump 63 (FIG. 2) with a surface that strongly absorbs radiantenergy in the range 157–250 nm (e.g., a block of hard-anodized aluminumwith a row of narrow vanes oriented in the direction of the reflectedlaser beam) is mounted inside the chamber 22. The beam dump 63 receivesradiant energy reflected from the surface 2 of the workpiece 4 duringprocessing. Additionally, a diagnostic laser beam 64 from a helium-neonlaser 66 may be introduced into the chamber 22 through the scanningoptics 48, and/or through the window 60. A monitor 68 could then beconfigured to receive a reflected diagnostic beam 64 to verify that thesurface 2 has been treated without having to remove the workpiece 4 fromthe chamber 22 (e.g., by interferometric or light scattering techniqueswell-known in the field of surface analysis).

The translation stage 42 can comprise components for the temperaturecontrol of workpiece 4 during processing. Such components can includeone or both of heating and cooling components 70 to maintain theworkpiece 4 at a desired temperature. Additionally, the translationstage 42 may include various sensors that monitor pressure 72,temperature 74, and gases 76 in the chamber 22.

For purposes of controlling the surface treatment sequence, thecontroller 44 produces the necessary signals to operate processingsystem 20 in accordance with the present invention.

FIG. 2 shows a block diagram of the controller 44. The controller 44includes a programmable central processing unit (CPU) 202 that isoperable with a memory 204, a mass storage device 206, an input controlunit 208, and a display unit 210. However, those skilled in the art willrealize that it would be a matter of routine skill to select anappropriate computer system to control processing system 20.Additionally, those of skill in the art will also realize that theinvention could be implemented using hardware such as an applicationspecific integrated circuit (ASIC) or other hardware circuitry. As such,it should be understood that the invention could be implemented, inwhole or in part, in software, hardware or both.

The controller 44 further includes well-known support circuits 214 suchas power supplies 216, clocks 218, cache 220, input/output (I/O)circuits 222 and the like. The I/O circuit is connected to a controlsystem bus 212. The bus 212 couples to the controller 44 the in-lineflow regulators 30 a and 30 b, gas values 32 a and 32 b, mass flowmeters 34 a and 34 b, exhaust pumps 38 a and 38 b, exhaust valves 40 aand 40 b, translation stage 42, laser controller 52, heating and coolingcomponents 70, chamber sensors 72, 74, and 76, and a chamber door 78.Optionally, an electrically driven mechanical arm 80, which moves theworkpiece 4 in and out of the chamber 22 through the chamber door 78 toand from a transport device/chamber 82, may be also controlled by thecontroller 44.

Other elements controlled by the controller 44 may include thefollowing: mixing chambers 36 a and 36 b for mixing different gases, andif used, transition motors (not shown) for the dispenser unit 8 andscanning optics 48. It is to be appreciated that the system controller44 provides signals to the chamber elements to cause these elements toperform operations for forming the reactive gas species in the subjectapparatus to accomplish atomic layer deposition, and othersemi-conductor processing, if desired.

The memory 204 contains instructions that the CPU 202 executes tofacilitate the performance of the processing system 20. The instructionsin the memory 204 are in the form of program code such as a program 300(FIG. 4) that implements the method of the present invention. Theprogram code may conform to any one of a number of different programminglanguages. For example, the program code can be written in C, C++,BASIC, Pascal, or a number of other languages.

The mass storage device 206 stores data and instructions and retrievesdata and program code instructions from a processor-readable storagemedium, such as a magnetic disk or magnetic tape. For example, the massstorage device 206 can be a hard disk drive, floppy disk drive, tapedrive, or optical disk drive. The mass storage device 206 stores andretrieves the instructions in response to directions that it receivesfrom the CPU 202. Data and program code instructions that are stored andretrieved by the mass storage device 206 are employed by the processorunit 202 for operating the processing system 20. The data and programcode instructions are first retrieved by the mass storage device 206from a medium and then transferred to the memory 204 for use by the CPU202.

The input control unit 208 couples a data input device, such as akeyboard, mouse, or light pen, to the processor unit 202 to provide forthe receipt of a chamber operator's inputs. The display unit 210provides information to a chamber operator in the form of graphicaldisplays and alphanumeric characters under control of the CPU 202.

The control system bus 212 provides for the transfer of data and controlsignals between all of the devices that are coupled to the controlsystem bus 212. Although the control system bus 212 is displayed as asingle bus that directly connects the devices in the CPU 202, thecontrol system bus 212 can also be a collection of buses. For example,the display unit 210 input control unit 208 and mass storage device 206can be coupled to an input-output peripheral bus, while the CPU 202 andmemory 204 are coupled to a local processor bus. The local processor busand input-output peripheral bus are coupled to form the control systembus 212.

Operation

Reference is also made to FIG. 4, which is a process flow chart of theprogram 300 that implements the ALD methodology according to the presentinvention. Prior to ALD processing, in step 310 an appropriate set ofreaction parameters are selected for use by the controller 44. Suchreaction parameters include, for example but are not limited to: energywavelength, energy density of the incident laser beam, gas composition,pressure and mass flow rates of precursor gas 5, input gas 10, purge gas14, and optionally, transmission gas 12 inside the reaction chamber 22,stage translation rate, and temperature of workpiece 4.

Once the reaction parameters are selected, the workpiece 4 in step 320is loaded into the chamber 16 through door 78, preferably from thetransport device/chamber 82, and positioned on the wafer chuck 24against banking pins 46, preferably by mechanical arm 80, with thesurface 2 to be treated facing up. The order of selecting reactionparameters in step 310 and loading in step 320 is non-critical, and maybe completed in any order or simultaneously.

In step 330, mechanical pump 38 a pumps on the chamber 22 until apressure of between about 1 and about 10 Torr is achieved. Next, in step340 the stage 42 translates the chuck 24 and workpiece 4 at a constantrate across the chamber 22 from a rear end 84 to a forward end 86 (FIG.2). When portion of the surface 2 of the workpiece is at its properposition for processing, in step 350 the controller 44 electricallyactivates gas values 30 a and 30 b and flow regulators 32 a and 32 b (inproper sequence). The controller 44 coordinates the delivery ofprecursor gas 5, input gas 10, and optionally transmission gas 12(FIG. 1) from gas cylinders 28 a and 28 b through the dispenser unit 8according to the selected reaction parameters. Additionally, in thisstep, the controller 44 coordinates the delivery of purge gas 14, andthe pumping on evacuation ports 12 a and 12 b by pump 38 b to preventmixing of the precursor gas 5 and input gas 10 flows.

In step 360, the controller 44 coordinates with the laser controller 52to deliver the laser beam 16 into the input gas flow 10. It is to beappreciated that controller 44 may be programmed to process the entiresurface of the workpiece or a targeted portion. In either case, thecontroller 44 provides for the delivery of the laser beam 16 accordingto the selected reaction parameters such that the high flux of point ofuse reactive gas species B is generated at the proper time to react withsurface reactant A at the selected locations of the surface 2 of theworkpiece 4. In most cases, the controller 44 will delay the generationof the high flux of point of use reactive gas species B until reactant Ais translated into its proper position for such interaction with gasspecies B.

In step 370, the controller 44 checks the formation of materialmonolayer S on the surface 2 of the workpiece 4. Such as, for example,if a desired layer thickness or quality is not detected by monitor 68,the above deposition processes may be repeated without removing theworkpiece 4 from the reaction chamber 22. If the above ALD process iscompleted, the gas valves 20 a and 20 b are closed, the chamber 22 ispurged in a conventional manner, and the workpiece 4 is then removedfrom the chamber 22 in step 380 to await a next workpiece 4 forprocessing in step 390.

In addition to the above-described ALD process, in certain situations itis may be desirous to chemically work the surface 2 of the workpiece 4with only the generated reactive gas species B before or after such ALDprocessing. Examples of such chemical treatments include, but notlimited to, etching, cleaning, removing photoresist, and otherapplications which will be apparent to those of skill in the art giventhe teachings herein. Depending on the kind of processing the workpiece4 is subjected to prior to being treated in chamber 22, and/or the typeof post-processing the workpiece 4 is to undergo, the surface 2 of theworkpiece 4 may be treated as many times as required without beingremoved from the chamber 16, and if desired, under different reactionconditions.

It is to be appreciated that the above described method and apparatus ofthe present invention increases ALD production rates. The increase inproduction rates results from permitting the working of the surface 2 ofthe workpiece 4 with the high flux of a point of use generated reactivegas species while ahead of forming a surface reactant with a flow of aprecursor gas without the need to completely purge or evacuate theentire reaction chamber.

Additionally, the present invention makes it possible to use two or moredispenser units to further increase the ALD process. In a multipledispenser unit arrangement, for each additional radiation beam anotherdispenser unit is provided, such as is illustrated by secondarydispenser unit 8′ and additionally radiation beam 16′ in FIG. 2. Sincethe function of the secondary dispenser unit 8′ and beam 16′ are thesame as dispenser unit 8 and beam 16 as described above, for brevity, nofurther discussion is provided as one skilled in the art wouldunderstand the use and benefit of such an arrangement.

In compliance with the statute, the invention has been described inlanguage more or less specific as to structural and methodical features.It is to be understood, however, that the invention is not limited tothe specific features shown and described, since the means hereindisclosed comprise preferred forms of putting the invention into effect.The invention is, therefore, claimed in any of its forms ormodifications within the proper scope of the appended claimsappropriately interpreted in accordance with the doctrine ofequivalents. Any modification of the present invention which comeswithin the spirit and scope of the following claims should be consideredpart of the present invention.

1. An apparatus for chemically treating a surface of a workpiececomprising: a supply of an input gas; a supply of a precursor gas; asupply of a purge gas; a dispenser unit adapted to expose the surface ofthe workpiece to a direct flow of said precursor gas for a surfacereactant formation, to provide a flow of said input gas over theworkpiece in a direction away from said precursor gas, and to providesaid purge gas between said precursor gas and said input gas to preventmixing of said precursor and input gases, said dispenser unit furtherhaving a pair of evacuation ports for evacuating said purge gas; and asource having optics which converge a beam of electromagnetic radiationin said flow of said input gas in close proximity to the surface of theworkpiece, but spaced a finite distance therefrom, to dissociate saidinput gas into a high flux of generated reactive gas species that reactswith said surface reactant to chemically treat said surface of saidworkpiece.
 2. The apparatus of claim 1, further comprising a flow of atransmission gas provided over said flow of said input gas, saidtransmission gas being substantially nonattenuating to preselectedwavelengths of said electromagnetic radiation.
 3. The apparatus of claim1 further comprising a structure for causing relative motion between thesurface of the workpiece, said dispenser unit, and said beam.
 4. Theapparatus of claim 1 further comprising a chamber for containing saidworkpiece and said gases during said processing, said chamber having awindow transparent to said electromagnetic radiation.
 5. The apparatusof claim 4 wherein said chamber further includes a workpiece temperaturesensor for measuring the temperature of the workpiece during processing;a pressure sensor for measuring the gas pressures in the chamber duringprocessing, and a gas sensor for monitoring at least said generatedreactive gas species.
 6. The apparatus of claim 1 wherein saidelectromagnetic radiation is ultraviolet radiation.
 7. The apparatus ofclaim 1 further comprising optics to focus said beam.
 8. The apparatusof claim 1, wherein said optics further expand a cross sectionaldimension of said beam into a wide scanning beam.
 9. The apparatus ofclaim 1 wherein said finite distance is less than a few mean-free-pathlengths of said generated reactive gas species.
 10. The apparatus ofclaim 1 wherein said chamber further comprising a pair of exhaust pumpfor pumping on said evacuation ports and for exhausting gases from saidchamber.
 11. The apparatus of claim 1 wherein said dispenser unitincludes a nozzle connected to said supply of input gas to provide alaminar flow across the surface of the workpiece.
 12. The apparatus ofclaim 1 wherein said chamber further comprises heating and coolingcomponents.
 13. The apparatus of claim 1 further comprising at least onemixing chamber.
 14. The apparatus of claim 1 further comprising acontroller adapted to control said chemical treatment according to aselected set of reaction parameters.
 15. The apparatus of claim 1further comprising a monitor adapted to monitor completion of saidchemical treatment.
 16. The apparatus of claim 1 further comprising abeam dump adapted to absorb reflected energy of said beam.
 17. Theapparatus of claim 1 wherein said dispenser unit is one of a pluralityof dispenser unit and said beam is one of a plurality of beams.